The origin and loss of the ubiquitin activating enzyme gene on the mammalian Y chromosome.
Mammalian sex chromosomes are thought to be descended from a homologous pair of autosomes: a testis-determining allele which defined the Y chromosome arose, recombination between the nascent X and Y chromosomes became restricted and the Y chromosome gradually lost its non-essential genetic functions. This model was originally inferred from the occurrence of few Y-linked genetic traits, pairing of the X and Y chromosomes during male meiosis and, more recently, the existence of X-Y homologous genes. The comparative analysis of such genes is a means by which the validity of this model can be evaluated. One well-studied example of an X-Y homologous gene is the ubiquitin activating enzyme gene ( UBE1 ), which is X-linked with a distinct Y-linked gene in many eutherian ('placental') and metatherian (marsupial) mammals. Nonetheless, no UBE1 homologue has yet been detected on the human Y chromosome. Here we describe a more extensive study of UBE1 homologues in primates and a prototherian mammal, the platypus. Our findings indicate that UBE1 lies within the X-Y pairing segment of the platypus but is absent from the human Y chromosome, having been lost from the Y chromosome during evolution of the primate lineage. Thus UBE1 illustrates the key steps of 'autosomal to X-specific' evolution of genes on the sex chromosomes.
Mitchell
M J
MJ
INSERM U406, Facult-e de M-edecine La Timone, 13385 Marseille, France. mitchell@ibdm.univ-mrs.fr
Wilcox
S A
SA
Watson
J M
JM
Lerner
J L
JL
Woods
D R
DR
Scheffler
J
J
Hearn
J P
JP
Bishop
C E
CE
Graves
J A
JA
D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D017931:DNA Primers; D017353:Gene Deletion; D006801:Humans; D008025:Ligases / Q000235:genetics*; D008297:Male; D008322:Mammals; D008969:Molecular Sequence Data; D010802:Phylogeny; D010987:Platypus; D011323:Primates; D011544:Pseudogenes; D044764:Ubiquitin-Activating Enzymes; D044767:Ubiquitin-Protein Ligases; D014960:X Chromosome; D014998:Y Chromosome
D017931:DNA Primers; D044767:Ubiquitin-Protein Ligases; D008025:Ligases; D044764:Ubiquitin-Activating Enzymes